1. Field of the Invention
The present invention relates to an input device mounted on a portable device or another electronic device and operated by causing an operation body such as a finger to come into contact with an operation panel.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 2009-87311 discloses an input device that detects a movement position using a capacitance sensor and detects an amount of pressing using a distortion sensor.
Further, Japanese Unexamined Patent Application Publication No. 2010-211399 discloses an information processing device having a pressure sensor and a capacitive touch panel. In Japanese Unexamined Patent Application Publication No. 2010-211399, a threshold of pressing force is set and presence or absence of pressing is determined
Japanese Unexamined Patent Application Publication Nos. 9-146689 and 8-328727 disclose that a sampling rate decreases (increases) when there is no coordinate input within a constant time. However, Japanese Unexamined Patent Application Publication Nos. 9-146689 and 8-328727 do not disclose an input device including a capacitance sensor, and a force sensor that measures pressing force.
Incidentally, there is a problem in that an output of the force sensor causes offset drift due to a change in a stress applied to a device with an input device, a change in a temperature, a change in a device shape over time, or the like. Further, when edges of the input device are held with one hand and an input operation surface is operated with fingers of the other hand, some load is applied to the force sensor at a time point at which the edges of the input device are held with the hand. Accordingly, the force sensor is not accurately driven, detection precision is degraded, and power consumption increases.
Information and timing used to efficiently perform calibration for offsetting an output of the force sensor in an input device including the capacitance sensor and the force sensor are not particularly described in each Patent Literature.